Frederik C. Roos

Hypoxia promotes ligand-independent EGF receptor signaling via hypoxia-inducible factor–mediated upregulation of caveolin-1

Caveolin-1 (CAV1) is an essential structural constituent of caveolae, specialized lipid raft microdomains on the cell membrane involved in endocytosis and signal transduction, which are inexplicably deregulated and are associated with aggressiveness in numerous cancers. Here we identify CAV1 as a direct transcriptional target of oxygen-labile hypoxia-inducible factor 1 and 2 that accentuates the formation of caveolae, leading to increased dimerization of EGF receptor within the confined surface area of caveolae and its subsequent phosphorylation in the absence of ligand. Hypoxia-inducible factor–dependent up-regulation of CAV1 enhanced the oncogenic potential of tumor cells by increasing the cell proliferative, migratory, and invasive capacities. These results support a concept in which a crisis in oxygen availability or a tumor exhibiting hypoxic signature triggers caveolae formation that bypasses the requirement for ligand engagement to initiate receptor activation and the critical downstream adaptive signaling during a period when ligands required to activate these receptors are limited or are not yet available.

Incidence and long-term prognosis of papillary compared to clear cell renal cell carcinoma – A multicentre study

AIM OF THE STUDY Papillary renal cell carcinoma (pRCC) is the second most common subtype of RCC after the conventional clear cell type (cRCC). However, its characteristics and prognosis have been less intensively investigated. The aim of our study was to examine the tumour characteristics and long-term prognosis of pRCC compared to clear cell RCC (cRCC). METHODS In total, 4941 evaluable patients were subjected to either radical nephrectomy or nephron-sparing surgery for pRCC or cRCC at five centres in Germany (University Hospitals of Hannover, Homburg/Saar, Mainz, Ulm and Marburg) between 1990 and 2010. RESULTS pRCC (n=565) and cRCC (n=4376) patients were comparable with regard to mean age, clinical symptoms, tumour differentiation and regional lymph node metastases. Patients with pRCC had a significantly higher rate of organ confined tumours (pT1-2, N/M0; 74.9% versus 62.9%), less synchronic visceral metastases (9.6% versus 15.2%), and a higher 5-year CSS rate than those with cRCC (85.1% versus 76.9%). Multivariate analysis identified the papillary subtype as a significant positive prognostic factor in localised (HR, 0.45) but as a negative prognostic factor in metastatic tumour stages (HR, 1.37). CONCLUSION pRCC can apparently be differentiated into two subgroups: an organ-confined/localised subgroup with a significantly better prognosis and an advanced/metastatic subgroup with a worse prognosis compared to cRCC.

Treatment efficacy and outcomes using a third generation shockwave lithotripter

To evaluate the clinical efficiency of a third generation electromagnetic shock wave lithotripter, the Lithoskop® (Siemens, Erlangen, Germany), regarding outcomes, stone disintegration, retreatment and complication rates. To compare the results of the Lithoskop with other currently available systems and the reference standard lithotripter, the HM‐3 (Dornier MedTech Europe GmbH, Wessling, Germany).

Deregulation of E2-EPF Ubiquitin Carrier Protein in Papillary Renal Cell Carcinoma

Molecular pathways associated with pathogenesis of sporadic papillary renal cell carcinoma (PRCC), the second most common form of kidney cancer, are poorly understood. We analyzed primary tumor specimens from 35 PRCC patients treated by nephrectomy via gene expression analysis and tissue microarrays constructed from an additional 57 paraffin-embedded PRCC samples via immunohistochemistry. Gene products were validated and further studied by Western blot analyses using primary PRCC tumor samples and established renal cell carcinoma cell lines, and potential associations with pathologic variables and survival in 27 patients with follow-up information were determined. We show that the expression of E2-EPF ubiquitin carrier protein, which targets the principal negative regulator of hypoxia-inducible factor (HIF), von Hippel-Lindau protein, for proteasome-dependent degradation, is markedly elevated in the majority of PRCC tumors exhibiting increased HIF1α expression, and is associated with poor prognosis. In addition, we identified multiple hypoxia-responsive elements within the E2-EPF promoter, and for the first time we demonstrated that E2-EPF is a hypoxia-inducible gene directly regulated via HIF1. These findings reveal deregulation of the oxygen-sensing pathway impinging on the positive feedback mechanism of HIF1-mediated regulation of E2-EPF in PRCC.

Renal cancer surgery in the elderly.

Purpose of review Renal cell carcinoma mainly develops in the sixth or seventh decade of life. As life expectancy increases, urologists have to deal with elderly patients presenting with renal cancer. The introduction of ablative techniques has even widened our armamentarium of treating elderly patients with renal cancer apart from the standard laparoscopic and open surgical procedures. Our review highlights the current literature focusing on the functional and oncological outcome of surgically treated renal cancer in elderly patients. Recent findings Despite the higher percentage of comorbidities, perioperative morbidity and declined renal reserve in elderly patients, radical or partial nephrectomy being performed open or laparoscopically for localized disease offers excellent functional and oncological outcome in this age group. Elderly patients seem to benefit more from laparoscopic procedures with lower rates of perioperative morbidity and faster convalescence compared with the open approach. Ablative techniques performed percutanousely may be promising for small renal masses in the future. Summary Surgical treatment of renal cancer performed laparoscopically or open is feasible and well tolerated in elderly patients, with low perioperative morbidity and a good overall survival rate. Long-term results for ablative techniques are still missing for this age group. Patients should be carefully selected for one of the surgical treatments according to their health, fitness, wishes and the experience of the referred centre.

Small renal cell carcinomas - How dangerous are they really? Results of a large multicenter study

AIM OF THE STUDY Modern diagnostic ultrasound and cross-sectional imaging has enabled the detection of increasing numbers of renal tumours. The aim of this study was to investigate the tumour- and patient-specific characteristics and prognosis of small renal cell carcinomas (RCCs) after surgical resection. METHODS The study included 2197 patients who underwent surgical resection of histologically confirmed RCC ⩽ 4 cm between 1990 and 2011. Median (mean) follow-up was 56.2 (65.5) months. RESULTS At the time of surgery, tumours were staged as pT ⩾ 3a in 175 (8.0%) cases, 134 (6.2%) were poorly differentiated and 75 (3.5%) were metastasised. The larger the tumour size, the higher was the risk of presenting with stage pT ⩾ 3a (p<0.001), poor tumour differentiation (p = 0.004), microscopic vascular involvement (p = 0.001) and collecting system invasion (p = 0.03). The 5-year cancer-specific survival (CSS) rate was 93.8% for stage pT1a versus 79.4% for stage pT ⩾ 3a (p<0.001), and it was 93.7% for G1-2 versus 76.8% for G3-4 differentiation (p<0.001). Multivariate analysis identified age in years (hazard ratio (HR) 1.04, p<0.001), metastatic disease (HR 12.5, p < 0.001), tumour differentiation (HR 2.8, p<0.001) and non-clear cell histology (HR 0.51, p = 0.02) as independent prognosticators for CSS in patients with small RCC. Interestingly, the 5-year cancer-specific mortality rate for pT1a N/M0 patients was 5.8%. CONCLUSIONS This large multicenter study has clearly shown that, though most small RCC have a low pathological stage and a good prognosis, there is also a small but significant subgroup of these tumours that are already locally advanced or poorly differentiated.

Oncolytic targeting of renal cell carcinoma via encephalomyocarditis virus.

Apoptosis is a fundamental host defence mechanism against invading microbes. Inactivation of NF‐κB attenuates encephalomyocarditis virus (EMCV) virulence by triggering rapid apoptosis of infected cells, thereby pre‐emptively limiting viral replication. Recent evidence has shown that hypoxia‐inducible factor (HIF) increases NF‐κB‐mediated anti‐apoptotic response in clear‐cell renal cell carcinoma (CCRCC) that commonly exhibit hyperactivation of HIF due to the loss of its principal negative regulator, von Hippel–Lindau (VHL) tumour suppressor protein. Here, we show that EMCV challenge induces a strong NF‐κB‐dependent gene expression profile concomitant with a lack of interferon‐mediated anti‐viral response in VHL‐null CCRCC, and that multiple established CCRCC cell lines, as well as early‐passage primary CCRCC cultured cells, are acutely susceptible to EMCV replication and virulence. Functional restoration of VHL or molecular suppression of HIF or NF‐κB dramatically reverses CCRCC cellular susceptibility to EMCV‐induced killing. Notably, intratumoural EMCV treatment of CCRCC in a murine xenograft model rapidly regresses tumour growth. These findings provide compelling pre‐clinical evidence for the usage of EMCV in the treatment of CCRCC and potentially other tumours with elevated HIF/NF‐κB‐survival signature.

Migration of renal tumor cells depends on dephosphorylation of Shc by PTEN.

The tumor suppressor PTEN is a phosphatase using FAK and Shc as direct substrates, and Akt as a key effector via PIP3. PTEN regulates cell migration and may influence metastases. We quantified PTEN in 135 clear cell renal cell carcinomas (ccRCC) by Western blot analysis and found statistically significant lower PTEN expression in patients who died, usually caused by metastases, within 5 years after surgery, compared to those surviving this time period. In athymic mice, PTEN transfected 786-O cells were injected into the tail vein and metastatic load of the lungs was quantified. We observed a strongly reduced metastatic load after PTEN transfection. For analyses of the PTEN activities, transfections with mutated PTEN genes were performed, leading to loss of lipid phosphatase activity and/or protein phosphatase activity, and of the C-terminal tail. Cell migration was analyzed in a Boyden chamber and phosphorylation of PTEN downstream targets Akt, FAK and Shc by Western blotting. 786-O cells transfected with the functional PTEN gene showed profoundly diminished migration. Transfection with a mutated PTEN isoform leading to loss of protein phosphatase activity, but not of lipid phosphatase activity, abolished this effect. Shc but not FAK seems to mediate this effect. These results show a critical role of PTEN in metastasis of RCC, depending on protein phosphatase activity via Shc. This new insight opens an alley of additional approaches complementing current cancer therapy and metastasis prediction in RCC.

Impact of several histopathological prognosticators and local tumour extension on oncological outcome in pT3b/c N0M0 renal cell carcinoma

To investigate the prognostic relevance of different histopathological features and local tumour extension in patients with pT3b/c N0M0 renal cell carcinoma (RCC), as recently new proposals of reclassifying tumour fat invasion in pT3b/c RCC have been made but the effect of other histopathological tumour characteristics and combinations thereof with tumour invasion has yet to be determined in these patients.

Sulforaphane inhibits proliferation and invasive activity of everolimus-resistant kidney cancer cells in vitro

Although the mechanistic target of rapamycin (mTOR) inhibitor, everolimus, has improved the outcome of patients with renal cell carcinoma (RCC), improvement is temporary due to the development of drug resistance. Since many patients encountering resistance turn to alternative/complementary treatment options, an investigation was initiated to evaluate whether the natural compound, sulforaphane (SFN), influences growth and invasive activity of everolimus-resistant (RCCres) compared to everolimus-sensitive (RCCpar) RCC cell lines in vitro. RCC cells were exposed to different concentrations of SFN and cell growth, cell proliferation, apoptosis, cell cycle, cell cycle regulating proteins, the mTOR-akt signaling axis, adhesion to human vascular endothelium and immobilized collagen, chemotactic activity, and influence on surface integrin receptor expression were investigated. SFN caused a significant reduction in both RCCres and RCCpar cell growth and proliferation, which correlated with an elevation in G2/M- and S-phase cells. SFN induced a marked decrease in the cell cycle activating proteins cdk1 and cyclin B and siRNA knock-down of cdk1 and cyclin B resulted in significantly diminished RCC cell growth. SFN also modulated adhesion and chemotaxis, which was associated with reduced expression of the integrin subtypes α5, α6, and β4. Distinct differences were seen in RCCres adhesion and chemotaxis (diminished by SFN) and RCCpar adhesion (enhanced by SFN) and chemotaxis (not influenced by SFN). Functional blocking of integrin subtypes demonstrated divergent action on RCC binding and invasion, depending on RCC cell sensitivity to everolimus. Therefore, SFN administration could hold potential for treating RCC patients with established resistance towards everolimus.